Unexamined Japanese Patent Application Kokai Publication No. H10-47651 (refer to Patent Literature 1) discloses a long magnetic circuit in which a plurality of permanent magnets are arranged with a space between so that surfaces having the same magnetic polarity face each other, and a plurality of magnetic yokes are inserted between each of the permanent magnets so that the permanent magnets and magnetic yokes come in close contact.
Unexamined Japanese Patent Application Kokai Publication No. H09-159068 (refer to Patent Literature 2) discloses a sandwiched-type magnetic circuit in which both sides in the magnetic pole direction of a permanent magnet are sandwiched between yokes, and is a magnetic adhesion member for pipelines that is used in a magnetic pipeline hoist that adheres to a solid magnetic body when hoisting and supporting pipeline.